Imidazolium salts and [Pt(cod)2]: from NHC hydrido complexes to the unprecedented olefinic tetrahedral cluster [Pt4(μ-H)(cod)4]BF4.

Whereas the bis(imine)imidazolium salt 1·Cl is a potential precursor to a NimineCNHCNimine pincer-type ligand, it reacted with [Pt(cod)2] to give the PtII NHC hydrido complex 3, in which chloride coordination and CNHCNimine chelation is preferred over pincer formation. Unexpectedly, reaction of 1·BF4 with [Pt(cod)2] afforded the unprecedented, 56 CVE tetrahedral cluster [Pt4(μ-H)(cod)4]BF4 (7), which was fully characterized. Imidazolium salts are ubiquitous sources of the much studied NHC ligands and not expected to lead to the formation of metal clusters.